1. Field of the Invention
The present invention relates to an ink-jet recording device using an ink that cures when irradiated with an actinic energy ray such as electron ray and ultraviolet ray and more particularly to a technique for coping with ink mist produced during an ejection of an ink droplet.
2. Background Art
In recent years, there has been proposed an ink-jet recording device (hereinafter also referred to as “actinic energy ray-curing ink-jet recording device”) which ejects onto a recording medium an ink that cures when irradiated with the actinic energy ray such as electron ray and ultraviolet ray using an ink-jet head and then emits energy onto the ink so that the ink is cured to form an image. The ink for use in the actinic energy ray-curing ink-jet recording device has characteristics satisfying the requirements that they cope with high speed recording on various recording media, show little bleeding to give a high precision image and be environmentally friendly. In particular, ink-jet recording devices using an ink that cures when irradiated with ultraviolet ray as actinic energy ray have industrially high applicability from the standpoint of compactness and thus are under development.
The ink-jet recording device comprises a plurality of piezoelectric elements, a diaphragm for transmitting oscillation generated by the piezoelectric elements, and a substrate having a plurality of nozzle holes corresponding to the piezoelectric elements for ejecting an ink droplet through the nozzle holes according to the oscillation of the diaphragm.
FIGS. 6A and 6B each are a schematic sectional view that illustrates the configuration of a nozzle of ink-jet head which ejects an ink. FIG. 6C is a side view that illustrates the shape of an ink droplet.
As illustrated in FIG. 6A, the substrate 1 comprises a nozzle plate 5 having a plurality of nozzle holes 3 formed therein and a channel forming member 9 defining a channel 7 communicating to the nozzle hole 3. When a voltage is applied to a piezoelectric element (not illustrated), the forward end of the piezoelectric element shows displacement in the thickness direction of a diaphragm 8. This displacement causes the change of the volume in the channel 7. As a result, the pressure in the channel 7 rises to cause an ink droplet 2 to be ejected through the nozzle hole 3 corresponding to the channel 7 as illustrated in FIG. 6B.
Since the curable ink has a relatively high viscosity, some part of the ink droplet 2 for image formation cannot fully follow the main body of the ink droplet 2 at the time when the ink droplet 2 is ejected and leave the nozzle hole, causing the simultaneous production of an unnecessary ink droplet 4 having a size of about 5 μm or less called “satellite” as illustrated in FIG. 6C. This satellite 4 can difficulty fly straight. As a result, the satellite 4 can be attached to image areas not related thereto or becomes an ink mist that can deteriorate the image quality or can be attached to totally unexpected sites on platen, nozzle plate and curing light source to impair the picture drawing stability. In particular, when recording is effected at a high speed, the produced amount of mist rises.
In order to solve this problem, JP-A-2004-188919 (the term “JP-A” as used herein means an “unexamined published Japanese patent application) discloses an actinic energy ray-curing ink-jet recording device which comprises a light-transmitting member detachably provided on the surface of an ink curing light source so that whenever the ink mist is attached to the light-transmitting member to reduce the amount of light, the light-transmitting member is renewed to prolong the life of the light source. Further, JP-A-2005-131922 discloses an actinic energy ray-curing ink-jet recording device which comprises a recording medium destaticizer provided on the ink-jet head carriage so that unnecessary attachment of mist to the recording medium can be prevented.
However, the related art techniques disclosed in the above cited patents find some difficulty in fully removing the effect of mist. When the mist is attached to unnecessary sites on the recording medium, the image quality is deteriorated. When the mist is attached to the nozzle plate, the nozzle hole is clogged to cause malejection leading to the deterioration of picture drawing stability.